A gas turbine is made up of a compressor, a combustor, and a turbine. The compressor produces high temperature and high pressure compressed air by compressing the air taken in at the air inlet. The combustor generates high temperature and high pressure combustion gas by supplying fuel to the compressed air, and combusting the fuel. The turbine includes a plurality of turbine vanes and turbine blades disposed alternately in a passage within a casing, and by driving the turbine blades with the combustion gas supplied to the passage, the turbine shaft that is connected to a generator is driven in rotation. The combustion gas that has driven the turbine is released to the atmosphere as exhaust gas.
Conventionally, for example, in the gas turbine described in Japanese Unexamined Patent Application Publication No. 2007-146787, a cooling air system (cooling air supply means) is disclosed that extracts compressed air that has been compressed by the compressor, cools it with a heat exchanger (TCA cooler), and supplies it to the turbine blades on the turbine side, thereby cooling the turbine blades.
For example, the gas turbine system described in Japanese Unexamined Patent Application Publication No. 2012-154290 discloses connecting a drain collection pipe between stages and at the outlet of the compressor that compresses air sprayed with a liquid, so that the liquid drain is discharged outside the system.
With the cooling air system disclosed in Japanese Unexamined Patent Application Publication No. 2007-146787, water accumulates at the outlet side of the heat exchanger, so there is a possibility of occurrence of corrosion. Also, it is not desirable that this corrosion be carried to the turbine side by the flow of cooling air. The drain collection pipe disclosed in Japanese Unexamined Patent Application Publication No. 2012-154290 is applied to the gas turbine system that includes the compressor that compresses air sprayed with a liquid. However, if this drain collection pipe is constantly used during operation of the gas turbine, compressed air bled from the compressor will also escape, so there is a possibility that this will lead to performance loss of the gas turbine.
The present invention solves the above problem, and it is an object of the present invention to provide gas turbine operation method and operation control device capable of removing water accumulated in a cooling air system while preventing performance loss of the gas turbine.